Iris diaphragm or simply iris. This is the device most cameras use to form and adjust the aperture. It consists of a series of overlapping thin metal blades that can swing toward the center of a hole in a flat metal ring.
IRIS DIAPHRAGM - Also sometimes simply known as "iris," a device inside a lens of thin overlapping metal leaves that move inwards or outwards, creating an aperture of variable size.
Iris Diaphragm
A continuously adjustable lens aperture consisting of interposed metal leaves.
A ...
[edit] Iris diaphragms versus other types
A Zeiss rotating diaphragm, 1906[1]. One diaphragm with five apertures.
had a iris diaphragm shutter and flash sync to 1/500 sec.
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Strictly, iris diaphragm. Device consisting of thin overlapping metal leaves pivoting outwards to form a circular opening of variable size to control light transmission through a lens.
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Diaphragm (iris diaphragm). The mechanism controlling the size of the lens opening and therefore the amount of light that reaches the film.
The plates in the iris diaphragm fold in on each other to shrink the aperture and expand out to make it wider.
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Sometimes applied to an iris diaphragm whose blades operate between lens elements. SHUTTER, FOCAL-PLANE-A shutter located near the focal plane and consisting of a curtain with a slot that is pulled across the focal plane to make the exposure.
Bausch & Lomb entered the shutter business in 1890 with their "Iris Diaphragm" a self-diaphragming type. They followed up with improvements to this model and with the less expensive "Unicum" of 1897.
7-blade Iris Diaphragm for better aperture control
Five-area spot meter and AF points (just like an F100)
256 zone matrix color white balance sensing
Coordinated adjustment of f/stop and shutter speed in Flexible Program mode ...
When Louis Jacques Mandé Daguerre joined his developments of new photographic processes they already used box cameras with iris diaphragm. Daguerre gave Niépce such a camera.
An alternative to the iris diaphragm is a diaphragm that consists of a series of "blades." This more primitive type of diaphragm was more prevalent in older camera models.
Aperture. The lens opening formed by the iris diaphragm inside the lens. The size of the hole can be made larger or smaller by the autofocus system or a manual control.
Aspect ratio. The ratio between the width and height of an image or image sensor.
An adjustable iris Diaphragm that controls, in part, how much light reaches the film or video tube.
The aperture is usually created by an iris diaphragm that is adjustable, enabling the aperture to be made wider or narrower, thereby letting in more or less light. The size of the aperture is expressed as an '-number, like '/8 or '/11.
-Exit pupil - image of the iris diaphragm formed on the back surface of a compound lens by the elements behind the aperture.
lens aperture
the adjustable opening in the iris diaphragm of a camera that determines the amount of light that will pass through the lens during exposure.
Diaphragm shutter
Between the lens camera shutter that performs the function of the iris diaphragm.
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Limiting aperture
The actual size of the aperture formed by the iris diaphragm at any setting. Determines, but usually differs from, the effective aperture.
It restricts the amount of light allowed into the camera. This term can also be applied to shutter types, i.e. iris diaphragm shutter, which is a set of interposing leaves, ...
 See also: Iris, Diaphragm, Lens, Camera, Light
  
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